Recently, attention has been focused on electrowetting (hereinafter also denoted as “EW”) devices using the electrowetting effect. Generally, in an EW device, a cell is filled with a polar liquid and a non-polar liquid which are not miscible with each other. By applying a voltage to the EW device, the interface between the polar liquid and the non-polar liquid changes and thus the light transmittance changes. Therefore, in order to increase the response speed of the EW device, it is necessary to reduce the viscosities of the polar liquid and the non-polar liquid to make them easier to flow upon application of a voltage.
However, when the viscosities of the polar liquid and the non-polar liquid are reduced, a problem of so-called backflow is likely to occur. Backflow herein refers to a phenomenon in which although a voltage continues to be applied to the EW device, the interface between the polar liquid and the non-polar liquid changes to approach an interface shape seen when no voltage is applied thereto.
For example, Patent Literature 1 proposes to prevent backflow by contriving a way to apply a voltage to the EW device.